The Internet protocol version 6 (IPv6) supports three transmission modes: Unicast, Multicast, and Anycast. The IPv6 protocol includes three kinds of addresses associated with a network device: unicast address, multicast address, and anycast address. Anycast is a communication mode where any sender corresponds to any receiver closest to the sender among several receivers in a topology structure. In contrast, multicast is a communication mode where a single sender corresponds to a set of selected receivers, whereas unicast is a communication mode where a single sender corresponds to a single receiver. In a routing process, the IPv6 protocol does not differentiate the unicast and anycast addresses. When responding to an anycast data packet, the node receiving the anycast data packet needs to take its own unicast address as the sender address in the header.
An IPv6 protocol-based anycast mechanism sets an identical anycast address to servers or other network devices with the same functions, namely the group address of the anycast group. With this solution, a message can directly reach a closest server or other network device, and at this time, if the message is also required to further forward to other anycast group members by the server or other network device, then the server or other network device in this connection is called a master node, and other anycast group members are called slave nodes. Here, the mast node and slave nodes are not equal therebetween. Correspondingly, if the message sent by a counterpart node (for example a sender) communicating with an anycast group to the anycast group is not required to be further forwarded to other nodes so long as it reaches any node (member) in the anycast group, then there is no differentiation between a mast node and slave nodes among the anycast group nodes. For example in consideration of load balance, there would be more than one register servers. By sending a register request message by a subscriber proxy to a preset universal address of all register services (for example an anycast group address), with the anycast mechanism, a closest server in the network will respond to the request, thereby the load balance problem can be effectively solved. It will be understood that during a communication process between a node and other nodes within an anycast group, each node in the anycast group can be a master node, dependent on which node within the group to be closest to the sender.
Currently, some applications of anycast (for example rendezvous point anycast group in a multicast routing device) have been widely supported by router vendors, where in an anycast group, each node is configured with the group address of the anycast group and the addresses of all member nodes (for example a router) in the anycast group. These configurations are prerequisite for normal operation of the anycast group. Till now, each node of an anycast group has always been configured manually, for example when a network integrator sells multiple content servers to a network content vendor and it requires anycast group configuration to these content servers, the field workers of the network integrator will configure the content servers one by one manually. If the number of anycast group members is more than 1, manual configuration of anycast group information is prone to inconstancy, which can cause connectivity problem, especially when the addresses are IPv6 addresses (since the addressed prescribed in the IPv6 are rather complex) or the members of the anycast group change (for example some new members need to be added in the anycast group or some old members need to be removed from the anycast group).
Apparently, there is a need to change the prevailing mode of manually configuring anycast group member nodes.